#include <bits/stdc++.h>
using namespace std;
 
int main() {
	int arr[] = {10, 5, 2, 7, 1, 9};
	int n = sizeof(arr) / sizeof(arr[0]);
	int k = 15;
	int pairs = 0;
 
	unordered_map<int, int> mp;
	//if XOR(i…j) = k then P(i-1) = k XOR k = 0 so we store 0 already in map beforehand
	//specially for cases where valid subarray starts from index 0 itself
	mp[0] = 1;                     // prefix XOR of empty subarray is 0
 
	int currentXor = 0;
	for (int j = 0; j < n; j++) {
		currentXor ^= arr[j];             
		int toFind = currentXor ^ k;	
		pairs += mp[toFind];
		mp[currentXor]++;
	}
	cout << pairs;
	return 0;
}
 

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